monitoring-plugins check_dns does not work with Busybox nslookup

The check_dns command in the monitoring-plugins package is broken with Busybox nslookup.

Without installing bind-host

$ /usr/lib/monitoring-plugins/check_dns  -H www.google.com -w 0.3 -c 1
DNS CRITICAL - '/usr/bin/nslookup -sil' msg parsing exited with no address

After installing the bind-tools package

$ /usr/lib/monitoring-plugins/check_dns  -H www.google.com -w 0.3 -c 1
DNS OK: 0.184 seconds response time. www.google.com returns 172.217.21.164,2a00:1450:400f:80a::2004|time=0.183755s;0.300000;1.000000;0.000000

We should add bind-tools as a dependency to monitoring-plugins or fix check_dns to work with Busybox